1. Technical Field
The present invention relates to a treatment instrument for an endoscope, and more particularly to a treatment instrument for an endoscope that is used for endoscopic submucosal dissection (ESD).
2. Background Art
Endoscopic mucosal resection is recognized as a minimally invasive and reliable treatment that is useful as a radical operation for neoplastic mucosal lesions such as early gastric cancer and early colorectal cancer. In recent years, a method referred to as endoscopic submucosal dissection (ESD) has been developed and brought into widespread use as a method that applies endoscopic mucosal resection to enable reliable en bloc resection of a lesion that extends over a wider area. In this method, en bloc resection of neoplastic mucosa is performed by dissecting submucosa between the mucosa and muscularis propria, after dissection of peritumoral mucosa. With this method, while it is possible to make a dissection line in the manner intended and to reliably resect a tumor, on the other hand there have been the problems that the method involves a high level of technical difficulty, the treatment requires skill and experience, and the treatment time is long.
Various treatment instruments for endoscopes have been proposed to solve these problems. For example, a treatment instrument for an endoscope disclosed in Patent Document 1 is a hook knife in which a high-frequency electrode at the tip is formed with a curved rod. By hooking the tip of the hook knife in mucosa tissue and drawing it into a sheath, the mucosa tissue is dissected. Further, a treatment instrument for an endoscope disclosed in Patent Document 2 is an IT knife in which an insulator is attached to the tip of an acicular surgical knife so that piercing of muscularis propria is prevented by the insulator. By using these treatment instruments for endoscopes, it is attempted to overcome even to a small degree some of the technical difficulty in performing endoscopic submucosal dissection.
Patent Document 1: Japanese Patent Application Laid-Open No. 2004-275641
Patent Document 2: Japanese Patent Application Laid-Open No. 8-299355